Current research aims to survey the various sensory, sympathetic and parasympathetic ganglia located in the head and neck for possible first order neurons located in primate and feline dental pulps. Methods include study of ganglia after retrograde transport of unlabeled and labeled (H3) horseradish peroxidase (HRP). Anterograde transport is also being studied using H3 leucine or proline. The nerve endings in the teeth are then defined by means of quantitative autoradiography. Again colchicine will be used to block axoplasmic transport of amino acids as it inhibits microtubule formation and the amount of H3 proline transported and utilized by cells will be determined. Since saltatory conduction will take place, neurotrophic action will be evaluated with and without sensory stimulation. This stimulation can be gained by cavity preparation. It is thus of interest to determine the role of nerve endings in contact with dentin forming cells in the odontogenic region of teeth with and without stimulation.